When it comes to supervillains, it's all about survival of the fittest. Sometimes a villain is introduced who's supposed to be a new Big Bad — but turns out to be a short-lived Little Awful instead. And sometimes, a villain who's supposed to appear once and then never be seen again catches fire and becomes the all-time great arch-nemesis.

Here are 10 famous villains who were supposed to be killed off or disappear early on — but instead, they became some of the world's most famous avatars of evil.

10. The Red Skull
Though Red Skull is one of Captain America's earliest and most well-known enemies, he originally wasn't supposed to show up again after his first appearance. But as the fan base grew, the character was brought back into the story. Later issues revealed that the original Red Skull was a fake, and introduced the true villain, eventually shown to be Johann Schmidt. According to Marvel's page on the character, the modern version of Red Skull didn't show up until Tales of Suspense #66 in 1965. (Here's a timeline describing the character's creation in more detail.)

9. Alex Krycek
This X-Files character appeared for seven seasons, but the producers considered killing him off in his first episode. But then actor Nicholas Lea ended up doing so well with the role
that Krycek became a mainstay, mostly working as one of Cancer Man's henchmen.

8. Shredder
Many fans of the Teenage Mutant Ninja Turtles cartoons probably can't imagine the series without Shredder as the main villain. However, he didn't last very long in the original comic books. Shredder himself was actually killed off early on in the story, though he did return in the form of worm clones. He became more strongly identified as the turtles' main antagonist when he was made the villain of the cartoon series.

7. Harley Quinn
Just like her sweetie Mr. J (see below), Harley Quinn was sort of a throwaway character originally. In her first appearance on Batman: The Animated Series, Harley is just a minor hench-person, who's supposed to appear briefly and then be gone forever. But the fans loved her so much that she was upgraded to a regular in the cartoon. As her popularity grew, Harley made her way into the comic book universe and became a full-fledged villain, eventually getting a backstory and her own henchmen. Here's one writer's timeline of Harley Quinn's history.

6. Spike
This popular Buffyverse character was only supposed to be around for a few episodes. The fans liked him so much that he was brought back and became a major villain for a while. Sure, he eventually teamed up with the Scoobies, but he did stay a recurring character.

5. Boba Fett
Boba Fett was a villain in the original Star Wars movies, but he had very little actual screentime. Somehow, this mostly silent bounty hunter became so popular that George Lucas even gave him a backstory in the prequels. Lucas has said that if he had known Fett would be so popular, he would have written the character a more interesting death. Though he never became the main villain, Boba Fett's popularity has made him a recurring character in the Star Wars Expanded Universe, including several storylines in which he survives the Sarlacc pit, more than once.

4. Scorpius
The Farscape villain was originally supposed to have a four-part arc in season one, and then vanish forever. But the producers were so impressed with Wayne Pygram's terrifying portrayal that they kept him around as the main villain.

3. Benjamin Linus
Originally, Michael Emerson was only supposed to appear for three episodes of Lost in season two, and then never be seen again. If everything had gone as planned, Henry Gale would have just disappeared after he escaped. However, the producers liked Emerson's performance so much that they wanted to keep him around. Emerson himself said that he never knew when he'd be on the show before he became a regular. Eventually, the Lost bosses made Emerson's role into a key character - the enigmatic morally ambiguous badass we all know as Benjamin Linus.

2. The Daleks
These iconic Doctor Who villains were originally just a one-off alien enemy, sneaked into the show despite a prohibition against "bug-eyed monsters" from the show's top producers. In fact, the Daleks are decisively destroyed at the end of their first story, with no chance they'll rear their shiny dome heads ever again. But then the audience loved the Daleks. Their debut caused a huge improvement in ratings for the show, which led to them becoming one of the Doctor's major enemies. The Daleks have since appeared in some capacity in 12 out of 26 seasons of the classic show, and every season of the modern series. And the Daleks' creator, Davros, had a similar arc, being killed off in his first appearance and then coming back to become a mainstay.

1. The Joker
The mad archvillain we all know and love was originally going to be killed off shortly after his debut=. At the end of the Joker's second appearance in Batman #2, he would have died after accidentally stabbing himself. Whitney Ellsworth, a DC editor, thought the Joker was too good a character to let die, so he had another panel drawn to show that the villain was still alive.